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by David Suzuki
Humans are remarkably efficient at killing. Although we often marvel at the ability
of big predators like tigers, wolves and sharks to efficiently dispatch their
prey, in terms of absolute numbers, none of these creatures holds a candle to
human beings. We are the best killers nature has ever made.
And it looks like we can add whales to our list of conquests. Most people know
that many whale species have been hunted to near extinction, but if a recent analysis
of whale populations is correct, humans may have slaughtered far more whales than
we ever imagined. Historic whale population estimates have always been based on
whaling logbooks compiled by ship captains since the mid 1800s. Conservation measures
have been predicated on these estimated "pre-whaling" numbers and countries
like Japan and Norway have been lobbying the International Whaling Commission
(IWC) to open up hunting to species that appear to have somewhat recovered.
But a report in the journal Science indicates that population estimates based
on logbook entries may be far too low. Those logs were always considered spotty
and many hunts were completely unrecorded. So a team from Stanford and Harvard
Universities turned to genetic variation in current whale populations to determine
historic numbers. The greater the variation, the larger the original numbers must
have been.
The analysis shows that pre-whaling numbers for many species may have been more
than 10 times greater than previously thought. The IWC, for example, estimates
that humpback whales in the North Atlantic used to number around 20,000, which
is twice the current population. However, genetic analysis shows that before large-scale
whaling began, humpback numbers may have actually been closer to 240,000. Other
species, like fin and minke whales, show similar robust pre-whaling populations.
If correct, these estimates show that whale populations have not remotely recovered
to their previous abundance. They also show that our oceans are capable of supporting
far greater populations of the world’s largest mammals. But because the
numbers are so different than previous estimates, the study is not without its
detractors. Some point out that, even if the numbers are correct, whale populations
could have plummeted prior to the start of commercial whaling.
Yet, according to other studies, these numbers are not remotely out of line with
what happens when humans go after natural resources. Just recently, a study found
that the island of Singapore has lost up to 73 percent of its species since industrialization.
New estimates on fish populations have found that, since industrial fishing began,
the oceans have lost 90 percent of their large, predatory fish. And in just 10
years, hunters in Asia have killed hundreds of thousands of saiga, an Asian antelope,
pushing the species to the brink of extinction.
Time after time, whenever human beings have turned our eyes to a new resource,
we have hammered away until it has all but disappeared. Subtle we are not. Even
when we had relatively small populations, humans managed to drive species to extinction.
Scientific evidence indicates that thousands of years ago, first in Australia,
then later in North America, small populations of humans armed with primitive
hunting tools managed to cause a mass extinction that eliminated more than half
of the continents’ large species.
With more than six billion people now inhabiting the planet, will we ever again
see a time when whales fill the seas and the oceans teem with life? Certainly
not anytime soon, but we at least have a benchmark as to the amazing amount of
life the world can support. We also know now of how quickly humans are capable
of eliminating that life. Now, for our own sake, the best predators the world
has ever known must sheathe our claws and make conservation an utmost priority.
Take the Nature Challenge and learn more
at www.davidsuzuki.org.
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